+ struct bcachefs_fid_with_parent *fid = (void *) _fid;
+
+ if (!bcachefs_fid_valid(fh_len, fh_type) ||
+ fh_type != FILEID_BCACHEFS_WITH_PARENT)
+ return NULL;
+
+ return d_obtain_alias(bch2_nfs_get_inode(sb, fid->dir));
+}
+
+static struct dentry *bch2_get_parent(struct dentry *child)
+{
+ struct bch_inode_info *inode = to_bch_ei(child->d_inode);
+ struct bch_fs *c = inode->v.i_sb->s_fs_info;
+ subvol_inum parent_inum = {
+ .subvol = inode->ei_inode.bi_parent_subvol ?:
+ inode->ei_subvol,
+ .inum = inode->ei_inode.bi_dir,
+ };
+
+ return d_obtain_alias(bch2_vfs_inode_get(c, parent_inum));
+}
+
+static int bch2_get_name(struct dentry *parent, char *name, struct dentry *child)
+{
+ struct bch_inode_info *inode = to_bch_ei(child->d_inode);
+ struct bch_inode_info *dir = to_bch_ei(parent->d_inode);
+ struct bch_fs *c = inode->v.i_sb->s_fs_info;
+ struct btree_trans *trans;
+ struct btree_iter iter1;
+ struct btree_iter iter2;
+ struct bkey_s_c k;
+ struct bkey_s_c_dirent d;
+ struct bch_inode_unpacked inode_u;
+ subvol_inum target;
+ u32 snapshot;
+ struct qstr dirent_name;
+ unsigned name_len = 0;
+ int ret;
+
+ if (!S_ISDIR(dir->v.i_mode))
+ return -EINVAL;
+
+ trans = bch2_trans_get(c);
+
+ bch2_trans_iter_init(trans, &iter1, BTREE_ID_dirents,
+ POS(dir->ei_inode.bi_inum, 0), 0);
+ bch2_trans_iter_init(trans, &iter2, BTREE_ID_dirents,
+ POS(dir->ei_inode.bi_inum, 0), 0);
+retry:
+ bch2_trans_begin(trans);
+
+ ret = bch2_subvolume_get_snapshot(trans, dir->ei_subvol, &snapshot);
+ if (ret)
+ goto err;
+
+ bch2_btree_iter_set_snapshot(&iter1, snapshot);
+ bch2_btree_iter_set_snapshot(&iter2, snapshot);
+
+ ret = bch2_inode_find_by_inum_trans(trans, inode_inum(inode), &inode_u);
+ if (ret)
+ goto err;
+
+ if (inode_u.bi_dir == dir->ei_inode.bi_inum) {
+ bch2_btree_iter_set_pos(&iter1, POS(inode_u.bi_dir, inode_u.bi_dir_offset));
+
+ k = bch2_btree_iter_peek_slot(&iter1);
+ ret = bkey_err(k);
+ if (ret)
+ goto err;
+
+ if (k.k->type != KEY_TYPE_dirent) {
+ ret = -BCH_ERR_ENOENT_dirent_doesnt_match_inode;
+ goto err;
+ }
+
+ d = bkey_s_c_to_dirent(k);
+ ret = bch2_dirent_read_target(trans, inode_inum(dir), d, &target);
+ if (ret > 0)
+ ret = -BCH_ERR_ENOENT_dirent_doesnt_match_inode;
+ if (ret)
+ goto err;
+
+ if (target.subvol == inode->ei_subvol &&
+ target.inum == inode->ei_inode.bi_inum)
+ goto found;
+ } else {
+ /*
+ * File with multiple hardlinks and our backref is to the wrong
+ * directory - linear search:
+ */
+ for_each_btree_key_continue_norestart(iter2, 0, k, ret) {
+ if (k.k->p.inode > dir->ei_inode.bi_inum)
+ break;
+
+ if (k.k->type != KEY_TYPE_dirent)
+ continue;
+
+ d = bkey_s_c_to_dirent(k);
+ ret = bch2_dirent_read_target(trans, inode_inum(dir), d, &target);
+ if (ret < 0)
+ break;
+ if (ret)
+ continue;
+
+ if (target.subvol == inode->ei_subvol &&
+ target.inum == inode->ei_inode.bi_inum)
+ goto found;
+ }
+ }
+
+ ret = -ENOENT;
+ goto err;
+found:
+ dirent_name = bch2_dirent_get_name(d);
+
+ name_len = min_t(unsigned, dirent_name.len, NAME_MAX);
+ memcpy(name, dirent_name.name, name_len);
+ name[name_len] = '\0';
+err:
+ if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+ goto retry;
+
+ bch2_trans_iter_exit(trans, &iter1);
+ bch2_trans_iter_exit(trans, &iter2);
+ bch2_trans_put(trans);
+
+ return ret;